HP ProDesk 400 G2.5 Maintenance And Service Manual page 49

5. Lift the fan sink from atop the processor.
When reinstalling the fan sink, make sure that its bottom has been cleaned with an alcohol wipe and fresh
thermal grease has been applied to the top of the processor.
CAUTION: Fan sink retaining screws should be tightened in diagonally opposite pairs (as in an X) to evenly
seat the fan sink on the processor to avoid damage that could require replacing the system board.
Fan sink 41